Conventional dishwashers include a main pump and fluid distribution system for circulating wash fluid within the wash chamber via spray arm assemblies or jets. A drain pump and associated drain system are used to drain the wash fluid from the chamber at the appropriate time in the wash cycle. The wash fluid sprayed onto the dishwasher items is collected in a sump located in a lower portion of the wash chamber, and water entering the sump is filtered through one or more pre-pump filters to remove soil and sediment from the washing fluid. In certain dishwashers, one of these filters may be a fine filter system in flow communication with the main pump assembly to remove soil and sediment of a smaller size than those filtered by an upstream coarse filter. The main pump assembly draws wash fluid from the sump to recirculate in the wash chamber, and the coarse and fine filters are used to continuously filter the water in the sump during the re-circulation process.
It is an inherent tendency of the filters to accumulate relatively large amounts of foreign matter over time, particularly at the point at which the water path through the fluid distribution system is of least resistance. This location generally corresponds to the section of the filter directly in line with main pump. Removal of this matter is necessary to ensure proper flow of the wash fluid through the system. Certain prior art systems rely on flushing of the filters with wash fluid that is redirected from the spray arm assemblies or dedicated jets. These systems are relatively complicated and have other inherent drawbacks.
Accordingly, other system designs for flushing filters in a dishwasher in a cost-effective and relatively simple manner would be welcome.